Getting geometry column integer SRID from a GeoPandas geodataframe?

Question

The primary answer to Adding GeoPandas Dataframe to PostGIS table? requires entering the geodataframe geometry column's integer SRID.

Getting the CRS attribute using the crs attribute like so

import geopandas as gpd
file_path = 'my_geodata.shp'

gdf = gpd.read_file(file_path)
geom_srid = gdf.geometry.crs['init']

gives a string like 'epsg:32616'.

The integer value can be extracted using regex:

geom_srid_num = re.search(r'\d+$', geom_srid)

But I'm not sure if the SRID is written in this format all the time, and if this method is reliable. Is there a more appropriate way to retrieve the integer SRID for a geodataframe geometry column?

Answer 1

In geopandas <= v0.6.3., gdf.crs returns a dictionary like {'init': 'epsg:EPSG_CODE'}. So, more appropriate way is to use tools of geopandas defined in geopandas.tools module.

geom_srid_num  = gpd.tools.crs.epsg_from_crs(gdf.crs)
print(geom_srid_num) # OUT: 32616 -> int

EDIT: As @snowman2 states in comment, epsg_from_crs is deprecated in geopandas v0.7.0. In this version gdf.crs returns pyproj.crs.CRS instance. Thus, the most appropriate way is to use to_epsg() method of CRS class.

gdf = gpd.read_file(file_path)
geom_srid_num  = gdf.crs.to_epsg()
print(geom_srid_num) # OUT: 32616 -> int